My UC Davis Wine Production notes state that the first decision of the winemaker is to conduct the fermentation with vineyard flora (should it really be fauna?) or with commercial yeasts. This topic was one that we discussed at length in the Wine Production forum and I bring it up again because it seems that natural wine relies on "wild or indigenous yeast" to conduct the fermentation. The yeast strains that are resident on grapes in sufficient numbers to conduct fermentation are Pichia, Kloekera, Dekkara, Candida and Brettanomyces. These wild yeast are not very alcohol tolerant (4-6% ethanol) and are SO2 sensitive, which is why winemakers use SO2 very early on to kill the wild yeast.
When I was taking the course, I asked the question: typical levels of Saccharomyces found as berry microflora are on the order of 10-2 (1 cell in 100mL) to 10-3(1 cell in 1 L or 1 part per million). If the initial inoculum should contain 105 to 106 cells/mL, how does one attain that level of Saccharomyces in a newly constructed winery?
One of my classmates responded giving me an "Ahhhh...I got it moment" when he wrote: if the doubling time is 6 hours, then in 2 days there would be just 1280 cells, but in 5 days, or 20 doublings that number would increase to 5,242,880. Assuming there's enough nutrients and they are balanced.
There is a really good article written by Jordon P. Ross on Wild Yeast in Winemaking that discusses California wineries using wild or uninoculated fermenations.
We will be a small winery (< 1500 cases) so I'm thinking I'd like to try uninoculated fermentations. Things to consider: Saccharomyces usually undergo at most 40 doublings. If a winery has used commercial yeast, it takes at least 3 years to rid the winery (i.e. on the equipment, from the pomace, etc) of the commercial yeast.
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